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  1. #1
    geraldatwork's Avatar
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    Inconsistency from Session to Session

    I always try to take good notes of my darkroom sessions. I try to record everything, and have a digital timer so my exposures are accurate. I try to be consistent always using with minor exceptions Ilford MG IV fiber paper and Dektol developer. I find when I go back to a negative using the same exposure,f-stop, burning etc there are more than minor differences almost to the point I am starting all over again. The exposures differ at times typically to 25% +- and also notice differences in contrast. Am I doing something wrong?

  2. #2
    ann
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    it is not unusal to have a bit of change but yours sounds more than the norm.
    Is your electrical current stable? What else is on the power lines you are using;i.e. power surges can create real issues.
    Using left over chemicals, or fresh? Developer changes with the number of prints and the length of time exposed to air; that will change your times and contrast.

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    Some of the variability may very well be in your enlarger light bulb and its power supply. Do you have a separate (and electrically stable) power suppy for the light source? What type of light bulb? If (for any reason) the light source is changing color temperature as it turns on and warms up, that could cause the problems you describe.
    Tom Hoskinson
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  4. #4
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    You don't say if when you go back to the negative if this is a different printing session or of you have this problem during one session, with the same dev, negative carrier height etc.

    If it is one print right after another and there is a change it is probably the electrical that is not consistant. The are voltage regulators as well as lux timers like Metrolux that measure the light output of the enlarger head and not just seconds of time.

    Maybe you could clarify by telling us your process.



    Michael McBlane
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  5. #5
    geraldatwork's Avatar
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    Thanks for the quick responses so far. I'm referring to another session a few weeks or months later. I don't think it is the enlarger or bulb because within a session there is consistency. For example if I make a change the result is consistent with that change. Also after I'm happy with all of the settings I'll usually make 2 or 3 duplicate prints developed/fixed one at a time and they are the same. In addition while the enlarger electric line is not dedicated there are no heavy drains on the line and I have a print stabilization device (from another manuf but I'm not 100% sure if it does anything) going into the enlarger. Also as far as enlarger height not only do I record the height but I'll take a a print of the previous session on that negative and will project the image on the print so everything lines up to give me the same size and crop.

    I am using a Saunders/LPL D6700 which I think has an halogen light. As I mentioned I use Dektol 1+2 and always throw it away after use. I never make more than about 15 8X10 prints prints so I don't think exhaustion is the problem. I generally don't keep unused developer more than the recommended time and more likely make fresh developer and throw out the last remaining part from the old batch. My gut feeling it is some inconsistency in the Dektol powder even though it doesn't make sense.

  6. #6
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    Is the temperature constant across sessions?
    Cheers, Shesh

    Not to know what happened before one was born is always to be a child - Cicero

  7. #7
    ann
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    if it is weeks and even months between sessions i would look at the way you are storing the developer. oxidation will occur if not carefully capped. Container should be filled up to the top and then use a piece of saran wrap under the cap. Some folks use glass marbles and dropped them in the container to bring the volume up to the top; others take the stock solution and divide into smaller containers.
    I personally, put developers in glass only, no plastic, keep in the dark and maintain volume level at it's highest point. But then i print often.

  8. #8
    geraldatwork's Avatar
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    The temperature of the developer might be one variable. My darkroom is in the garage so in the winter the room is about 60 degrees but I place the tray on top of a space heater to try to get it to around 72 degrees which takes about an hour to get down to around 63-64 to where I put it back again. In the summer the garage can go up to 80 degrees but I place a larger tray with ice in some water to keep the developer +- 5 degrees of 68. I keep the print in the developer for around 2 1/2-3 minutes to wards the longer side if the developer is cooler and to wards 2 1/2 if the developer is warmer. Very frustrating.

  9. #9
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    Monitor the line voltage. It will respond not only to load variation in your house, but to others on the same line. The variation may be long or short term. Use a light meter to check for variations, which will also occur due to aging of the bulb.
    Gadget Gainer

  10. #10
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    It's most likely that a combination of factors are the cause. From the description of your working practises there are a few inconsistencies and whilst it may not be any one that is the cause the cumulation of a few will have an effect. As has already been pointed out the voltage fluctuation is probably the biggest factor which is one of the reasons that I use cold cathode with an RH Designs Compensating Timer. It does work, for when the farm dryer is switched on in the harvest it drains a lot of power but the timer picks it up and increases the length of the exposure to allow for the lower voltage. My prints are very consistent as a result.

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